Process for dyeing textiles made from acrylonitrile-containing polymers



United States Patent PROCESS FOR DYElNG TEXTILES MADE FROM ACRYLONITRILE-CONTAINING POLYMERS Archie G. Schoonover, South Charleston, Theophilus A. Feild, Jr., Charleston, and John H. Purse, South Charleston, W. Va., assignors to Union Carbide and Carbon Corporation, a corporation of New York No Drawing. Application August 23, 1952, Serial No. 306,068

4 Claims. (Cl. 8-55) This invention relates to the dyeing of textile articles formed from or containing filaments or fibers made of acrylonitfile-containing polymers. It has especial utility for the dyeing of articles formed from polyacrylonitriles and from copolymers of acrylonitrile with a wide range of other polymerizable unsaturated compounds containing an olefinic double bond, such as vinyl chloride, vinyl acetate, 2-vinylpyridine, acrylamide, methyl-alpha methacrylate, alphamethacrylamide, and mixtures of such polymers and/ or copolymers.

It long has been known that resinous acrylonitrilecontaining polymers are highly resistant to dyestulfs and that, as the acrylonitrile content of copolymers of acrylonitrile with such other polymerizable compounds increases, the difficulty of dyeing becomes greater.

In recent years important advances have been made in the art of dyeing articles made from acrylonitrile-containing resinous polymers by a novel and commercially practicable process wherein textile and other articles made therefrom are treated with an aqueous liquid containing a small amount of a compound yielding cuprous ions. This so-called copper technique of dyestutf ap-. plication, which is described inour pending application, Serial No. 217,317, filed March 23, 1951, is believed to represent the first commercially practicable method for dyeing articles made from acrylonitrile-containing r'es'inous polymers to deep shades with acid-type, direct-type and water-soluble acetate-type dyestuffs.

The aforesaid method of dyeing articles made from acrylonitrile-containing polymers which involves the use of cuprous compounds sometimes presents certain dyeing difliculties, resulting in the loss or ineffective use of either or both the costly dyestuif and the copper compound, and an imperfectly dyed article. For example, under certain circumstances during the dyeing operation the cuprous ions, formed from the cupric compound which is introduced in excess into the bath liquid in a soluble almost colorless form at a selected point in the dyeing operation, may change into a finely divided yellow, red or brown oxide powder. The latter may deposit upon the article being dyed and give erratic dyeings. Moreover, depending upon the acid used in the dyeing and the Wetting agents employed, one or more of these forms of solid products may exist during the dyeing. While bath temperatures around 212 F. are most favorable for the fixation of the dyestuffs on the article, it is in this temperature range that the reactions forming the insoluble copper oxides and other copper complexes not available for dye fixation also are greatest. The formation of insoluble matter, when it occurs in a dyebath, presents a crocking problem, reduces the effectiveness of the cuprous compounds, and may cause unpredictable dyeing results. The use of an undue excess of the copper compound thus not only is costly but also is detrimental to the uniformity of the dyeing and to the light-fastness and crock-fastness of the dyed article. 1

The present invention is based in important part upon the discovery that textiles and other articles formed from or comprising filaments, fibers, yarns and the like made from resinous acrylonitrile-containing polymers may be uniformly and readily dyed to any desired shade of color, using water-soluble dyestuffs of the acid-type, direct-type and/or water-soluble acetate-type, while avoiding at all times the presence in the dyebath of a substantial excess of the copper compound over that required to provide a dyed article of a selected color shade. This is accomplished by initiating the dyeing operation within a dyebath in the substantial absence of a copper compound and thereafter, while the dyeing of the article is continued at temperatures near but substantially below the strain-release temperature at which objectionable change in shape of the article being dyed occursand preferably within the range between around 200 F. and around 212 F.-slowly' introducing small successive amounts of an aqueous liquid containing cuprous ions, such as those hereinafter described, preferably dropwise, to the dyebath and contents until the desired depth of color is attained in the article being dyed, and then promptly discontinuing the addition of the said aqueous liquid. In this manner material savings of the treating agents are effected. Moreover, various difiiculties arising when an undue excess of the copper compound is present in the dyebath at any one time are avoided.

Among the.more important objects of the invention are the following: to provide for the dyeing in novel manner of-textile and other articles made from or containing acrylonitrile-containing resinous polymers with one or more water-soluble dyestuffs of the acid-type, direct-type and/or water-soluble acetate-type, and mixtures thereof; to provide in novel manner during the dyeing of such articles with said dyestuffs for controlling the rate of exhaustion of the dyestuff andvfor improving the appearance and color shade of the dyed article; to provide in the dyeing of such articles with said dyestufi's by means of the copper-dyeing technique for minimizing the amount of dyestutf and copper compound required to yield a satisfactorily dyed article of a desired color shade; and to provide, in the dyeing of articles made from acrylonitrilecontaining polymers, by processes involving the use of a cuprous compound, for maintaining the copper compound in active available form not injurious to the shade and levelness of the dyeing. I 7

According to one preferred form of the present invention for the dyeing of fibers, yarns and other textile articles made from resinous acrylonitrile-containing polymers, the articles are scoured in known manner with an aqueous solution of a suitable detergent and a wetting agent. The scoured article, after rinsing with Water, is placed in an aqueous bath'in the ratio by weight of one part of the article to from 10 to parts of water, and commonly in a ratio of around 1:15. One or more Watersoluble dyestuffs selected from the class consisting of the acid-type, direct-type and water-soluble acetate-type dyestuffs then is added, with or without a dispersing and leveling agent and/or a swelling and penetrating agent for the resin article. The dyebath temperature then is raised slowly to between 200 F. and the boiling point. Temperatures of F. to 200 F; likewise can be used when a swelling or penetrating agent for the resin also is employed. The dyeing also can be conducted under superatmospheric pressure in an enclosed pressure-, tight furic. acid: isused, althoughmther. mineral, acids suclras. hydrochloric acid and phosphoric acid, andbrganic acids,

such. as.formic. acidand acetic acid can. be used.

There then is added,slowly to the hot dyebath in successive small increments; preferably dropwise, over a.

PGIlOdiCOIIlIHOIllY around -minutes,. a. liquid containing a cuprous compound ina. concentration usually ranging from around 0.2% to.2-.0%- or more, basedupon the weight of said liquid, dispersed, or dissolved in water. Cuprousv sulfate, sulfite,, chloride acetate, formate and the like are. useful in the process. It is convenient to use in. the process. more or less freshly prepared aqueous liquids. containing cuprousions, such as can be made by separately dissolving. inawater, preferably. at room temperature, cupric. sulfateor. other cupricw compound and a reducing. agent for. the cupric. compound in amount required to. reducev the latter tothe cuprous form.-such as; the zincor alkali metal formaldehyde-sulfoxylates, hydroxylamine sulfate, sodiumbisulfite, dihydrazine sulfate,

glyoxal, and the: like-combining. the two solutions, and.

slowly adding portions of the resultant mixture to the hot dyebath.

The: dyeing of the article is continued at the aforesaidtemperatures, and preferably at around the boiling point of the bath during the slow. addition of the treating liquid and until the desired shade of color is secured in the article, oruntil the dye is exhausted. Additional dyestuff can be. added to the bath if and when desired, since in the present process there is neverpresent in the bath such an excess of cuprous compound as to precipitate the dyestuif prematurely or to deposit upon the article. Usually, for best results, the dyeing is conducted for a period of at least one hour at the boiling point of the dyebath. The amount of the cuprous compound-or of the corresponding mixture of cupri'c compound and reducing agent employed -depends in considerable degree upon the particular acrylonitrile-containing' polymer being, dyed, the particular dyestuff employed, the depth of color desired, and the temperature and other conditions of the dyeing operation, as will be evidenced from the examples here presented.

The addition to the dyebath of around 40% to 200% or more of an alkali metal sulfate at some stage in the dyeing operation, and commonly after the treating liquid containing the cuprous ions has been added, serves effectively when used to minimize delustering of the article. The dyed article then is scoured at 140 F. in a solution containing a detergent, is rinsed with water, and then is air-dried at temperatures commonly around 160 F. Further relustering may be done, if necessary, by heating the dry dyed article at 240 F.-250 F. with dry heat for a brief period.

In certain forms of the invention, preferred for securing dyeings with deep shades of color on textile articles made from polymers of the foregoing types, and particularly when using dyebath temperatures around 175 F. to 180 F., the dyebath conveniently can have added thereto a dyeing assistant capable of penetrating or swelling the surface of the article. Many swelling or penetrating agents are useful. Particularly effective are derivatives of diphenyl and of benzylphenyl containing one or more hydroxy groups attached to a carbon atom or atoms of an aromatic ring or rings. Such compounds also can contain one to two chlorine atoms attached to a carbon atom or atoms of the same or different aromatic rings. Among suitable compounds are the ortho-, mand pphenylphenols, the o,o,-, o,p'-, and m,m,'-biphenols,

p-benzylphenol, p,p'dihydroxydiphenylmethane and the p,p'-'dihydroxydichlorodiphenylmethanes. Such swelling agents, when used, can be added to the dyebath conveniently in the form of their alkali metal salts in alkaline solution prior to acidification of the bath. P-phenylphenol, a representative dyeing assistant, is highly effective in proportions around 1% to 15% of the dry weight of the article being dyed. When only medium or light shades of color are desiredimthe dyeings, a swelling agent for the resin article is not required, and ordinarily is not used.

It often is desirable to have present inthe dyebath from 1% to. 3% or more of a dispersing. and leveling agent, preferably one of the. cationic or of the anionic type. Highly effective are the water-soluble. cationic products of the condensationofl ethylene. oxide with. an organic amine. Such a product is being marketed under the trade name Peregal OK. Such products can be made by the process disclosed in United States Patent No. 2,214,352.

The following examples serve to illustrate the invention. In the examples, and throughout the specification and. claims, all parts are given-in terms of weight, and all percentages; are based upon the dry weight of the article being dyed, unless otherwise specified. Each dyebath hada pH withintherange from 2 to 7- during the dyeing in the presence of the cuprous. compounds.

EXAMPLE 1.

A quantity of staple fibers made from a copolymer of acrylonitrile and vinyl chloride containing around 40% of acrylonitrile in the polymer and having a specific viscosity at 20 C. of about 0.26, was secured in an aqueous solution of a detergent, and then was placed in an aqueous dyebath containing, 4% Xylene Milling Blue GL (color index No. 833), 3% of sodium p-phenylphenoxide as penetrating agent, and 1% of Peregal OK as leveling agent, and, the pH of the dyebath was adjusted to between 4 and 5 with sulfuric acid, The bath was heated to boilingtemperature and dyeing proceeded for 30 minutes, after which there was slowly added dropwise to the boiling dyebath during 3 0 minutes an aqueous liquid containing cuprousions, and the dyeing continued until the desired colorshade was scoured in the fibers. The dyed fibers were scoured and then dried at 250 F.

The treating liquid was made by mixing at room temperature copper sulfate, water, and zinc formaldehydesulfoxylate in proportionsyielding an aqueous liquid containing 0.25% of copper sulfate and,0.l25% of zinc formaldehyde-sulfoxylate,based upon the Weight of the liquid. In this. dyeing, reduced copper corresponding to 0.82% of cupric sulfate based on the fiber, weight was required for maximum dye exhaustion and color depth in the fibers. The dyeing proceeded at an even rate to a medium blue shade.

EXAMPLE 2 Dyeing the same fibers described in Example 1, and following the method described in that example, with the exception that 10% of sodium p-phenylphenoxide was used, and that the dyestutf used was 4% of Anthraquinone Blue. SWF Cone, an acid-type of prototype No. 12, and the dyeing was conducted at a maximum dyebath temperature of F., similar results were secured. The dyeingproceeded at an even rate to the desired shade. Cuprous ions corresponding to 4.9% of cupric sulfate were required to give the desired shade of blue.

EXAMPLE 3 Dyein th sam fibers des r b d p Example 1, and following h PI9PF d sst bs n h t a with the exception that the, dyestutf used was 4 o of'Anthraquinone Blue AB (color indexNo. 1075), andthe. treating liquid was made by mixing, water, cupric sulfate and hydroxylamine sulfate in proportions --to yield a liquid containing 0.25% of cupric sulfate and 0.125 of hydroxylamine sulfate, based upon the weight of the said liquid, cuprous ions corresponding to 2.4% of c'upric sulfate were required to give the fibers a good shade of blue. The dyeing proceeded at an even rate to the desired shade.

EXAMPLE 4 Fibers of this kind described in Example lwere dyed, following the procedure described therein, with the exception that the dyestuif used was 4% Navy 43 Conc. (color index No. 304), and the treating liquid containing cuprous ions was room temperature water, cupric sulfate and dihydrazine sulfate in proportions to yield a liquid containing 0.25% of cupric sulfate and 0.125% of dihydrazine sulfate, based upon the weight of the liquid. In the example, 4.2% of cupric sulfate, reduced with 2.1% dihydrazine sulfate, was required to give the fibres the desired good Navy shade. The dyeing proceeded uniformly.

EXAMPLE 5 A quantity of staple fibers of the type described in Example 1 was scoured in an aqueous solution of a detergent. The scoured fibers then were agitated in an aqueous dyebath at a bath to dry fiber weight ratio of 15:1. The bath contained 5% of Cloth Red G (color index No. 249), an acid-type dyestuif, 1.5% of Peregal OK," and suflicient concentrated sulfuric acid to adjust the dyebath pH to 3.5-4. The dyebath then was brought to a boil, and a treating liquid containing cuprous ions made as hereinafter described, was added dropwise to the boiling dyebath during 30 minutes, and dyeing was continued at the boil for a total of 90 minutes. The dyed fibers then were scoured, and finally dried at 240 F. The fibers were dyed to a good depth of color, and had good wash-fastness and crock-fastness. and bright.

In an identical run, with theexception that all of the treating liquid was added to the unheated dyebath at of Xylene Milling,

made by mixing at The color was clearone time prior to being brought to the boil, the dyeing 1 was less clear and bright, and a lighter shade of color was secured.

The treating liquid containing cuprous ions used in this example was prepared by forming an aqueous liquid containing 2% of cupric sulfate and 1% of zinc formaldehydesulfoxylate, based on the weight of the fibers.

EXAMPLE 6 A quantity of staple fibers recited in Example 1, after scouring, was agitated in an aqueous dyebath at a bath to dry fiber weight ratio of 15:1, said bath containing sodium p-phenylphenoxide produced by the reaction of 2.25% of p-phenylphenol and 0.75% of sodium hydroxide. The bath also contained 0.5% of Peregal OK as leveling agent. Concentrated sulfuric acid was added until the bath had a pH of 3.5-4 and 5% of Cloth Red G (color index No. 249) then was added. The dyebath was brought to a boil, and a treating liquid containing cuprous .ions and made exactly like that described in Example 5 was added dropwise to the hot dyebath during 30 minutes. The dyeing was continued at a boil for a total of 90 minutes. The dyed fibers, after scouring, and then drying at 240 F., were clear and bright, had good color depth, and excellent wash-fastuess and'crockfastness.

EXAMPLE 7 L A-quantity of spun yarn, made from a commercially available acrylonitrile-containing resin believed to contain over 85% and up to 100% of acrylonitrile in .the polymer and being marketed under the designation Orlon 'lype 41, was scoured, andthe said yarn was placed in color index No. 833), and 1% of Peregal OK. The

pH of the dyebath was reduced to-around 4-5, and the dyebath brought to a boil. After 30 minutes at this temperature an aqueous treating liquid containing cuprous ions was slowly added dropwise to the bath during 30 minutes to obtain dyestuif exhaustion. The treating liquid was prepared as a cold aqueous solution containing 0.25% of cupric sulfate and 0.125% of zinc formaldehydesulfoxylate, based upon the weight of the said liquid. Dyeing at the boil was continued until the yarn had attained thedesired color shade. In this example, reduced copper ions corresponding to 3.6% of cupric sulfate were required to provide a dyed yarn having the optimum color value. The dyeing proceeded at an even rate to a good blue shade.

EXAMPLE 8 Following the procedure described in Example 7, with the exception that the article dyed was a quantity of sp-un yarn made from a resinous copolymer of acrylonitrile and-vinyl chloride containing around 68% of acrylonitrile in the polymer and having a specific viscosity at 20 C. of 0.41, reduced copper corresponding to 3.1% of cupric sulfate was required to give maximum dyestutf exhaustion and yarn color value. The dyeing proceeded at an even rate to yield the desired blue shade.

EXAMPLE 9 A woven fabric made from continuous filament acrylic fiber being marketed commercially under the trade name Orion, and understood to contain or more of acrylonitrile in the polymer, was scoured, and placed in an aqueous dyebath containing 6% of Anthraquinone Blue SWF Conc., 150%. The pH of the bath was adjusted to 5, and the dyebath broughtto boiling. After 15 minutes an aqueous treating liquid was slowly added dropwise to the boiling dyebath during a 30 minute period. The treating liquid contained 5% of cupric sulfate and 2.5% of zinc formaldehydesulfoxylate, based upon the fabric weight, dissolved in water at room temperature. After continuing the dyeing at the boil for 45 minutes, the dyed fabric was scoured, and dried at 250 F. It had a good medium shade of color, with good wash-fastness and crock-fastness. The dyestuff ex- EXAMPLE 10 A woven fabric, made from an acrylic fiber spun from a resinous copolymer of acrylonitrile and vinyl acetate, being marketed under the trade name Acrilan and believed to contain around or more acrylonitrile in the polymer, was scoured and then placed in an aqueous dyebath containing 2% of Peregal OK," 4% of Anthraquinone Blue SWF Conc., 6% of sodium pphenylphenoxide, and enough sulfuric acid to adjust the pH to 5. The dyebath was brought to a boil. After 15 minutes an aqueous treating liquid was slowly added dropwise to the bath during 30 minutes. The treating liquid was prepared by dissolving 5% of cupric sulfate and 2.5% of zinc formaldehydesulfoxylate, based upon the fabric Weight, in water at room temperature to form an aqueous solution containing about 1.0% of cupric sulfate, based upon the weight of said liquid. The dyeing then was continued at the boil for 45 minutes. The dyed fabric was scoured, and dried at 250 F. It had a medium shade of blue, and good wash-fastness and crock-fastness. The dyestuif exhausted at an even rate. In comparable dyeings where the copper-containing treating liquid was not used, only a pastel color shade was obtained.

Among the many the following:

dyestuffs useful in the process are,

xyl ne Milling Yellow P Xylene illing Yellow 261 Xyl ne F t s 2G Xylene Light Rubine 26S Calcoid Neutral Brown RS Anthralan Red BA-CF- P3210 Chromaven Milling Qran ge G. Cone 274 Alizarine Light Brown BL Alizarine Light Green GSN Alizarine Light Gray RLL Alizarine Light Red 'R Alizarine Sky Blue BS-CF 108E. Alizarine Cyanine Green GHN-CF 1078 Brilliant Alizarine Light Red 4B Sulfonine Red G 430 Calcochrome Alizarine Gray- 2BLS Pr. 206 Xylene. Fast Rubine 3GP Pr. 412 Amacicl Red 3B Conc 208 Sulfonine Orange GS Pr. 151 Sulfonine Yellow. 26 642 Cloth Red G. 249 Croceine Scarlet MOO 252 Anthraquinone Violet R 1080 Anthraquinone Blue SWF 150% Pr. 12 Supramine Yellow 3GLA-CF Pr. 474 Calcocid Milling Red 3R Conc 275 Direct-type dyestufis Trade Name: Color index No. Calcomine Brilliant Yellow Conc 365 Fastusol Brown LBR Fastusol Red 413A 278 Calcodur- Yellow BL Conc 814 Calcodur Yellow NN 814 Water-soluble acetate-type dyestufls Trade Name: Color index No.

Solacet Fast Violet RS Solacet Fast, Yellow GS Solacet Fast Scarlet B 125 1 u Solacet Fast Green 268 Solacet Fast Blue 2BS Solacet Fast Orange ZGKS Solacet Fast Red SBGS 1 This dycstutf has the structure agent therefore, canbeinade without departing from the invention. The swelling agent, when used, can be added to. thebath from a solution thereof in a. suitable solvent, or it may be; addedin the form of a niicronized powder.

The specific viscosities of the resins referred to herein Were determined at 20 C. using an Ostwald viscosimeter in, accordance with the formula:

Specific viscosity;

Viscosity of a solution of 0.1 gram of theresin in, 50.00., of solvent.

Viscosity of the solvent;

8 In de rmining h se spastic isccsi inu cyclolnmm as. u wi h here ins Qt? Examine 1 o- 6, and dimo hyls v 'memide was. used tn the resinqf Example. 8. The. specific, viscosityof the; resin is a direct. function of its a age olecular weight.

T his application is: a continuation'in-part of our pending application, Serial No. 217,317, filed March 23, 1951'.

The invention is susceptible of modification within the scope of the appended claims.

We claim:

1. Process for dyeing textile articles made from polyacrylonitriles and copolymers of acrylonitrile with at least one other polymerizable compound containing a single olefinic double bond, which comprises treating such an article with an aqueous dyebath having a pH within the range from 2.0 to 7.0'and containing a water-soluble dyestuff selected from the class consisting of the acid-type, direct-type and water-soluble acetate-type dyestuffs, and slowly adding to said aqueous dyebath successive small amounts of a compound yielding cuprous ions while heating the article in the dyebath containing cuprous ions at a temperature of at least 175 F. for at least 15 minutes.

2. Process for dyeing textile articles made from resinous polyacrylonitriles and copolymers of acrylonitrile with at least one other polymerizable compound containing a singleolefinic double bond with water-soluble dyestuffs, in the presence of sufiicient cuprous ions to provide ready exhaustion of the dyestuif, while minimizing the amount of copper compound required to. produce a dyed article of selected color shade, which comprises treating such an article with an aqueous dye'oath having a pH within the range from 2 to. 7 and containing a water-soluble dyestufi selected from the class consistingof theacid-type, direct-type and water-soluble acetate-type dyestuffs, and

' slowly adding to such dyebath during a period of at least 10 minutes successive small amounts of an aqueous solution of a copper compound yielding cuprous ions whilc heating the article in the dyebath at a temperature of at least 175 E, anddiscontinuing the slow addition of the copper compound to the solution when the article has attained approximately the desired shade of color.

3. Process for dyeing textile articles made from resinous ,polyacrylonitriles and copolymers of acrylonitrile with at least one other polymerizable compound containing a single olefinic double bond with water-soluble dyestuffs in the presence of sufficient cuprous ions to provide ready exhaustion of the dycstuff, while minimizing the amount of copper compound required to produce a dyed article of selected color shade, which comprises treating such an article with an aqueous dye'oath having a pH within the range from 2 to 7 and containing a water-soluble dyestulf selected from the class. consistingof the acid-type, directtype and. water-soluble acetatetype dyestuffs, and slowly adding to such, dyebath during a period of at least 10 minutes, successive small increments of an aqucoussolw tioncontaininga copper compound yielding cuprous ions, while heating the article; in the dyebath at a temperature of at least 200 F, and discontinuing the addition of the solution of the copper compound to the dychath. when the. article has attained approximately the desired shade ofco-lor;

4., Processtor dyeing textile articles made. from resinous polyacrylonitriles and copolymers of acrylonitrile with at least one othen polymerizablc compoundcontaining a single olefinicidouble bond with water-soluble dyestuffs in the presence of sufficient cuprous ions to provide ready. exhaustion of the dyestuif, while minimizing the amount of copper compound required to produce a dyed article of selected color shade, which comprises treating such an article with an aqueous dycbath having a pH within the range from 2' to 7 and containing a water-soluble dycstufi selectedfrom. the class consisting of theacid-type, directtype and. water-soluble acetate-type dyestufis, together; with a swelling agent for the resin, and slowly addingntoi 7 suchdyehath during aperiod of at least 10 minutcs successive small increments of an aqueous solution contain mg a cupric compound and a reducing agent for the latter yielding cupnous ion s', while heating :the article in the dyebath at a temperature of at least'175' F., and dis-' continuing the addition of the solution of the copper 5 compound to the dyebath when the said article has attained approximately the desired shade of color.

References Cited in the file of this patent Chemistry of Synthetic Dyes, by K. Venka-taraman, vol. 2, pp. 812-815, published 1952, N. Y. C., by Academie Press. 1

Br. Rayon and Silk Journal for February 1954, p. 77. Tech. Bulletin for March 1951, pp. 45-52, published in Wilmington, Del., by Du Pont.

Rayon & Syn. Tex. for December 1951, pp. 62, 63. 

1. PROCESS FOR DYEING TEXTILE ARTICLES MADE FROM POLYACRYLONITRILES AND COPOLYMERS OF ACRYLONITRILE WITH AT LEAST ONE OTHER POLYMERIZABLE COMPOUND CONTAINING A SINGLE OLEFINIC DOUBLE BOND, WHICH COMPRISES TREATING SUCH AN ARTICLE WITH AN AQUEOUS DYEBATH HAVING A PH WITHIN THE RANGE FROM 2.0 TO 7.0 AND CONTAINING A WATER-SOLUBLE DYESTUFF SELECTED FROM THE CALSS CONSISTING OF THE ACID-TYPE, DIRECT-TYPE AND WATER-SOLUBLE ACETATE-TYPE DYESTUFFS, AND SLOWLY ADDING TO SAID AQUEOUS DYEBATH SUCCESSIVE SMALL AMOUNTS OF A COMPOUND YIELDING CUPROUS IONS WHILE HEATING THE ARTICLE IN THE DYEBATH CONTAINING CUPROUS IONS AT A TEMPERATURE OF AT LEAST 175* F. FOR AT LEAST 15 MINUTES. 